1. Field of the Invention
This invention relates to an image forming system having an image forming device, such as an electrophotographic printer, for forming an image on a recording medium, and a stacking device connected to the image forming device for receiving the printed recording medium on which the image is formed.
2. Description of Prior Art
Generally, an image forming system has an image forming device, a paper feeding device and a paper stacking device. The image forming device receives a sheet of paper and forms an image thereon. After the image is formed, the printed sheet is transported to the paper stacking device.
Recently, in the stacking device art there has been recognized a need to rapidly stack a plurality of sheets, because the image forming device forms the image on the sheet at a high speed. For example, to this end, Japanese Patent disclosure (Kokai) No. 63-171770. Ono et al., discloses a stacking device having a mechanism which receives a plurality of printed sheets. In the stacking device, there are a sheet tray and an elevator mechanism. The elevator mechanism moves the sheet tray vertically in response to the height of the stacked sheets.
The stacking device, further, has a second tray positioned over the sheet tray. When it is impossible to stack the next printed sheet on the sheet tray, such as in a paper full condition, a cover open condition, and the like, the sheet is transported to the second tray.
Moreover, the types of systems are increasing in which a stacking device as an optional device is connected to the image forming device. In the case in which the stacking device is an optional device, it is necessary that an exit tray be arranged in the image forming device because some user will often buy the image forming device only.
However, there is a problem in this system. That is, when the exit tray is arranged in the image forming device, the transporting path from the image forming device to the stacking device is longer than that of such a device in which the sheet tray is arranged in the stacking device. Further, in the case there is an another optional device between the image forming device and the stacking device, the transporting path is longer than that of this system. Consequently, if the sheet is being transported in the transporting path when the stacking operation becomes impossible, sheet jamming will occur in the transporting path.